[U-Boot] [PATCH] efi_loader: bootmgr: support BootNext and BootCurrent variable behavior

[AKASHI Takahiro]

See UEFI v2.7, section 3.1.2 for details of the specification.

With my efishell command[1], you can try as the following:
  => efi boot add 1 SHELL ...
  => efi boot add 2 HELLO ...
  => efi boot order 1 2
  => efi bootmgr
     (starting SHELL ...)
  => efi setvar BootNext =H0200
  => efi bootmgr
     (starting HELLO ...)
  => efi dumpvar
  <snip ...>
  BootCurrent: {boot,run}(blob)
  00000000:  02 00                    ..
  BootOrder: {boot,run}(blob)
  00000000:  01 00 02 00              ....

Using "run -e" would be more human-friendly, though.

[1] https://lists.denx.de/pipermail/u-boot/2018-November/346450.html

Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
 lib/efi_loader/efi_bootmgr.c | 37 +++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
index 2aae12e15456..a9b774df6c91 100644
--- a/lib/efi_loader/efi_bootmgr.c
+++ b/lib/efi_loader/efi_bootmgr.c
@@ -118,11 +118,21 @@ static void *try_load_entry(uint16_t n, struct efi_device_path **device_path,
 	parse_load_option(&lo, load_option);
 
 	if (lo.attributes & LOAD_OPTION_ACTIVE) {
+		u32 attributes;
 		efi_status_t ret;
 
 		debug("%s: trying to load \"%ls\" from %pD\n",
 		      __func__, lo.label, lo.file_path);
 
+		attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			     EFI_VARIABLE_RUNTIME_ACCESS;
+		size = sizeof(n);
+		ret = rs->set_variable(L"BootCurrent",
+				       (efi_guid_t *)&efi_global_variable_guid,
+				       attributes, size, &n);
+		if (ret != EFI_SUCCESS)
+			goto error;
+
 		ret = efi_load_image_from_path(lo.file_path, &image);
 
 		if (ret != EFI_SUCCESS)
@@ -146,16 +156,41 @@ error:
 void *efi_bootmgr_load(struct efi_device_path **device_path,
 		       struct efi_device_path **file_path)
 {
-	uint16_t *bootorder;
+	u16 bootnext, *bootorder;
+	u32 attributes;
 	efi_uintn_t size;
 	void *image = NULL;
 	int i, num;
+	efi_status_t ret;
 
 	__efi_entry_check();
 
 	bs = systab.boottime;
 	rs = systab.runtime;
 
+	/* BootNext */
+	size = sizeof(bootnext);
+	ret = rs->get_variable(L"BootNext",
+			       (efi_guid_t *)&efi_global_variable_guid,
+			       NULL, &size, &bootnext);
+	if (!bootnext)
+		goto run_list;
+
+	attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
+		     EFI_VARIABLE_RUNTIME_ACCESS;
+	size = 0;
+	ret = rs->set_variable(L"BootNext",
+			       (efi_guid_t *)&efi_global_variable_guid,
+			       attributes, size, &bootnext);
+	if (ret != EFI_SUCCESS)
+		goto error;
+
+	image = try_load_entry(bootnext, device_path, file_path);
+	if (image)
+		goto error;
+
+run_list:
+	/* BootOrder */
 	bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
 	if (!bootorder)
 		goto error;
-- 
2.19.1